Field of the Invention
The present invention is directed in general to semiconductor devices and methods for manufacturing same. In one aspect, the present invention relates to the fabrication of optical interface structures for routing optical signals to and from one or more mounted semiconductor devices or integrated circuits.
Description of the Related Art
Integration of optical communication systems into integrated circuit (IC) chips is considered a promising solution for overcoming physical limitations in high-frequency, high-density information systems. But in addition to the difficulty of integrating optical communication systems within IC chips, there are challenges associated with integrating optical interconnects between IC chips. In this area, there have been proposed a number of optical chip-to-chip interconnect systems, such as free-space connections, embedded fibers, guided wave connections, and embedded multimode waveguides used in printed circuit boards or other conventional backplane connectors. Even so, there remain many technical challenges to realizing efficient optical coupling between optical communication systems at each IC chip, including reducing positional or signal alignment inaccuracies in the optical path (that can decrease the coupling efficiency or lead to transmission failure), accounting for perpendicular alignment between an IC chip relative to the backplane interconnect, and the fabrication costs and complexities associated with forming optical interconnects (e.g., active optoelectronic devices) that are capable of coupling optical signals between IC chips. Attempts have been made to overcome these challenges by using fiber optic waveguides and/or external mirrors or deflectors in the printed circuit board or off chip to optically transfer information between different IC chips, but these solutions present their own difficulties, costs, and control requirements. For example, fiber optic waveguides not only have additional costs and complexity, but may also impose bandwidth limitations on chip-to-chip communications. In addition, the cost for designing and assembling the optical transmitter, external mirrors or deflectors, and the optical receiver, as well as the requirements for achieving alignment with these components to ensure a desired level of information transmission, may be cost prohibitive. Finally, control circuits and external signal deflection structures can increase the overall system complexity, thereby reducing possible signal bandwidth between different IC chips. As a result, the existing solutions for interconnecting optical communication systems from different IC chips make the implementation of high bandwidth optical interconnects extremely difficult at a practical level.
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the drawings have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for purposes of promoting and improving clarity and understanding. Further, where considered appropriate, reference numerals have been repeated among the drawings to represent corresponding or analogous elements.